We have a new problem with our 03 vibe. There is tons of condensation inside the car that freezes up, but I have found only one small leak in the back that accounted for about one or two ounces of water.

The seats feel a bit damp, but I can find no leaks in the car. The carpet is dry. I did notice after a hard rain that the two moonroof drain tubes in the back had no water at all in them. Wondering of there is a clog somewhere.

Make sure the recirc button is off, allowing outside dry air to circulate.

Run the A/C with recirc on and check under the car to make sure condensation is draining. Related: check the condensation drain outlet hose for debris/ice that could be clogging it- one symptom is a damp passenger side carpet (if you have all weather floor mats, you'll need to check underneath)

Snowy boots/coats can bring in a lot of moisture that will condense on cold windows- using the defrost/floor setting with A/C to dry out the car helps...